Compressive Strength of Fly-Ash-Based Geopolymer Concrete by Gene Expression Programming and Random Forest

By Muhammad Khizar Khan, Shazim Ali memon, Furqan Farooq, Muhammad Faisal Javed, Fahid Aslam, Rayed Alyousef. Advance in Civil Engineering, 2021

201 citations recorded by the source corpus.

<jats:p>Fly ash (FA) is a residual from thermal industries that has been effectively utilized in the production of FA-based geopolymer concrete (FGPC). To avoid time-consuming and costly experimental procedures, soft computing techniques, namely, random forest regression (RFR) and gene expression programming (GEP), are used in this study to develop an empirical model for the prediction of compressive strength of FGPC. A widespread, reliable, and consistent database of compressive strength of FGPC is set up via a comprehensive literature review. The database consists of 298 compressive strength data points. The influential parameters that are considered as input variables for modelling are curing temperature <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>T</mi> </mrow> </mfenced> </math> </jats:inline-formula>, curing time <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>t</mi> </mrow> </mfenced> </math> </jats:inline-formula>, age of the specimen <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>A</mi> </mrow> </mfenced> </math> </jats:inline-formula>, the molarity of NaOH solution <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>M</mi> </mrow> </mfenced> </math> </jats:inline-formula>, percent SiO2 solids to water ratio <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5"> <mfenced open="(" close=")" separators="|"> <mrow> <mo>%</mo> <mtext> </mtext> <mi>S</mi> </mrow> <mo>/</mo> <mi>W</mi> </mfenced> </math> </jats:inline-formula> in sodium silicate (Na2SiO3) solution, percent volume of total aggregate (<jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6"> <mtext> </mtext> <mo>%</mo> <mtext> </mtext> <msub> <mrow> <mi>A</mi> </mrow> <mrow> <mi>G</mi> </mrow> </msub> </math> </jats:inline-formula>), fine aggregate to the total aggregate ratio <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>F</mi> <mo>/</mo> <mrow> <msub> <mrow> <mi>A</mi> </mrow> <mrow> <mi>G</mi> </mrow> </msub> </mrow> </mrow> </mfenced> </math> </jats:inline-formula>, sodium oxide (Na2O) to water ratio <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M8"> <mfenced open="(" close=")" separators="|"> <mrow> <mi>N</mi> <mo>/</mo> <mi>W</mi> </mrow> </mfenced> </math> </jats:inline-formula> in Na2SiO3 solution, alkali or activator to the FA ratio <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9"> <mfenced open="(" close=")" separators="|"> <mrow> <msub> <mrow> <mi>A</mi> </mrow> <mrow> <mi>L</mi> </mrow> </msub> </mrow> <mo>/</mo> <mrow> <msub> <mrow> <mi>F</mi> </mrow> <mrow> <mi>A</mi> </mrow> </msub> </mrow> </mfenced> </math> </jats:inline-formula>, Na2SiO3 to NaOH ratio <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10"> <mfenced open="(" close=")" separators="|"> <mrow> <msub> <mrow> <mi>N</mi> </mrow> <mrow> <mi>s</mi> </mrow> </msub> </mrow> <mo>/</mo> <mrow> <msub> <mrow> <mi>N</mi> </mrow> <mrow> <mi>o</mi> </mrow> </msub> </mrow> </mfenced> </math> </jats:inline-formula>, percent plasticizer (<jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M11"> <mo>%</mo> <mtext> </mtext> <mi>P</mi> </math> </jats:inline-formula>), and extra water added as percent FA <jats:inline-formula> <math xmlns="http://www.w3.org/1998/Math/MathML" id="M12"> <mfenced open="(" close=")" separators="|"> <mrow> <msub> <mrow> <mi>E</mi> </mrow> <mrow> <mi>W</mi> </mrow> </msub> <mtext>%</mtext> </mrow> </mfenced> </math> </jats:inline-formula>. RFR is an ensemble algorithm and gives outburst performance as compared to GEP. However, GEP proposed an empirical expression that can be used to estimate the compressive strength of FGPC. The accuracy and performance of both models are evaluated via statistical error checks, and external validation is considered. The proposed GEP equation is used for sensitivity analysis and parametric study and then compared with nonlinear and linear regression expressions.</jats:p>

Subfields: Civil and Structural Engineering

View Paper: https://www.semanticscholar.org/paper/b01dfd9fb0976ad52b0bee9223101a360fc822c4